Radiocondenser



Dec. 24, 1929. P. ZARAT}E. JR 1,740,850

RADIO CONDENSER Filed Jan. 13. 1926 anwnm I feel Z araie, Jr;

Cuban,

Patented Dec. 24, 1929 UNITED STATES PATENT OFFICE ONE-HALF T0 LAWRENCEW. ANDREWS, OF KANSAS CITY, MISSOURI RADIOCONDENSER Application fliedJanuary 13, 1926. Serial No. 81,004.

My invention relates to improvements in variable condensers such as areemployed in connection with radio transmittin and re dio receivingapparatus, and one object is to obtain in a single instrument anydesired capacity and thereby avoid the necessity of connecting up anumber of units where a large capacity is needed.

A further object is to provide a variable condenser of more compact andeconomical construction than other variable condensers of like capacity.

Another object is to rovide a variable condenser whereby the finestselective tuning may be had with a single instrument and thereby avoidthe necessity of employing several units which have to be connected inor out of a circuit to secure the desired selections.

In order that the invention ma be fully understood, reference will nowbe ad to the accompanying drawing, in which:

Fig. 1 is an elevation of one form of the condenser.

Fi 2 is a cross section on line 2-2 of Fig. 1, looking in the directionof arrow a.

Fig. 3 is a cross section on line 22 looking in the direction of arrow6.

Fig. 4 is an elevation of a modified form of the condenser.

Referring more particularly to the form disclosed by Figs. 1 to 3,inclusive, 2 designates a frame consisting preferably of insulating endbars 4 and 6, and rods 8 connecting said end bars 4 and 6.

10 and 12 designate two rotatable conductors fixedly mounted uponmetallic shafts 14 and 16, respectively, the former of which isjournaled in the end bars 4 and 6 of the frame. The shaft 16 has one endjournaled in the bar 4 and its opposite end fixed to a dielectric shaft17 journaled in the bar 6. One end of the shaft 14 projects through apanel 18 and is provided with a fixedly mounted knob 20 carrying a dial22, which coacts with a hxed pointer 24 on the panel 18 for indicatingthe extent to which the shaft 14 is rotated by said knob 20. The shafts16 and 17 are rotated in unison with the shaft 14 through in tcrmeshinggears 28 and 30, fixedly mounted upon the shafts l4 and 17,respectively.

32 and 34 designate contact members secured to the end bar 4 by suitablemeans such as screws 36 and 38, respectively. The contact member 32presses at one end against the adjacent end of the shaft 14 and isprovided at its opposite end with a bindin post- 40 for holding acircuit wire 41, and the contact member 34 presses at one end againstthe adjacent end of the shaft 16 and is provided at its opposite endwith a binding post for hold ing a circuit wire 43.

44 designates a flexible conductor secured at one end to the rotatableconductor 10 and at its opposite end to a dielectric plug 46 countersunkin the rotatable conductor 12 near one end thereof. The plug 46 ispreferably spaced as far as possible from that end of the rotatableconductor 10 to which the flexible conductor 44 is attached to cause thelatter to wind in an advancing spiral or screw-like form upon therespective rotatable conductors instead of in superimposed eonvolutions,and said flexible conductor 44 is preferably made long and narrow sothat its capacity will gradually increase as it is wound upon therotatable conductor 12 instead of abruptly increasing and therebyrendering the condenser unfit for fine tuning. In order to prevent ashort circuit from the flexible conductor 44 to the rotatable conductor12 the latter is coated with a suitable dielectric varnish.

In practice the condenser is charged with current flowing over the wires41 and 43, and tuning in is effected by unwinding the flexihle conductor44 from the rotatable conductor 10 and winding it in an advancing spiralupon the rotatable conductor 12, by rotating the knob 20. By winding theflexible conductor 44 in an advancing spiral, as hereinbet'ore stated,any selection may be had between zero, when substantially all of theflexible conductor 44 is wound upon the rotatable conductor 10, andmaximum capacity when substantially all of said flexible conductor 44 iswound upon the rotatable conductor 12,115 the capacit graduallyincreases as the flexible con ductor is wound upon the rotatable (ouductr 12. Likewise the capacity gradually decreases as the flexibleconductor 44 is wound upon the rotatable conductor 10.

In the modified form disclosed by Fig. 4, the flexible conductor 44 ismounted upon a single rotatable conduct-or, which, however. is dividedinto two sections 10 and 12 by insulation 13. The shaft upon which therotatable conductor is fixedly mounted is also di vided by theinsulation 13 into two sections [4 and 16, the latter being providedwith a fixedly mounted knob 20" carrying a dial 22 coacting with apointer 24. fixed to the panel 18-. The shaftsections 14 and 16" arejournaled in the dielectric end bars 4 and 6", respectively, of theframe 2. A contact member 32 bears against the outer end of the shaftsection 14 and is provided with abinding post 40 for holding a circuitwire 41, and a contact member 34" bears at one end upon the shaft- 16and is provided at its opposite end with a binding post 42 for holding acircuit wire 43.

The flexible conductor 44 is connected at one end to the section 10 ofthe rotatable conductor and at its opposite end to a dielectric plug 46countersunk in the section 12 of said rotatable conductor, and saidflexible conductor 44* is guided from one section to the other of therotatable conductor by a rod 15 secured to the end bars 4" and 6, sothat said flexible conductor will be wound in an advancing spiral.

As in the form shown by Figs. 1 t0 3, inclusive, the capacity of thecondenser may be increased from zero to maximum by unwinding saidflexible conductor from the section 10" and windin it upon the section12 of the rotatable conductor.

From the foregoing description it is apparent that important features ofthe invention reside in winding the flexible conductors 44 and 44 inadvancing spiral or screw like convolutions instead of in superimposedconvolutions, and in making said flexible conductors comparatively longand narrow. While I have shown two forms of the invention, I reserve allrights to such other forms and modifications as properly fall within thespirit and scope of the invention as claimed.

Having thus described my invention, what I claim and desire to secure byLetters Patent, is:

1. In a variable condenser, two rotatable conductors arranged side byside, a flexible conductor connected to one of said rotatable conductorsnear the left end of the latter and to the other rotatable conductornear the right end of the latter so that it may be wound in an advancingspiral upon either of said rotatable conductors, and a dielectricinterposed between said flexible conductor and one of said rotaryconductors.

2. In a variable condenser, two rotatable conductors, a flexibleconductor in the form of a strip connected to said rotatable conductorsin such manner as to wind .upon either in the form of an advancingspiral, a dielectric coating on one of said rotatable conductors forinsulating the latter from the flexible conductor, means for rotatingsaid rotatable conductors, and calibrated means for determining theextent of said rotation.

3. In a variable condenser, a rotatable conductor, a flexible conductorarranged to be wound u on or unwound from said rotatable con actor tovary the capacity of the condenser, a dielectric interposed between saidconductors, means for causing said flexible conductor to wind upon therotatable conductor in an advancing spiral, and means for rotating therotatable conductor and determining the extent of such rotation.

4. Ina variablecondenser, a rotatable conductor, a relatively long andnarrow flexible conductor arranged to be wound upon or unwound from saidrotatable conductor to vary the capacity of the'condenseiga dielectricinterposed between said conductors, means for causing said flexibleconductor to wind upon the rotatable conductor in an advancing spiral,and contacts in circuit with said rotatable conductor.

5. A variable condenser consisting of two rotatable conductors, aflexible conductor arranged to be wound in an advancing spiral uponeither of said rotatable conductors to vary the capacity ofthecondenser,.a frame in which said rotatable conductors are journaled, adielectric interposed between the flexible conductor and one of therotatable conductors, and gearing for simultaneously rotating'therotatable conductors.

In testimony whereof I aflix my signature.

PAUL ZARATE, JR.

